In-Mold Label, and Labeled Resin-Labeled Article

ABSTRACT

An in-mold label comprising an olefinic resin substrate layer (A) having a wetting index (α) of from 34 to 74 mN/m and a heat-sealable resin layer (B) with an antistatic layer having a wetting index (β) of from 30 to 54 mN/m, wherein the absolute value of the initial frictional charge voltage of the substrate layer (A) relative to a sheet offset printing blanket is from 0 kV to 15 kV. This label has good workability in printing, cutting and blanking even in a low-humidity environment.

TECHNICAL FIELD

The present invention relates to in-mold production of labeled,resin-molded articles in a mode of differential pressure molding, blowmolding, injection molding, vacuum molding or air-pressure molding, andconcretely relates to an in-mold label and a labeled, resin-moldedarticle.

BACKGROUND ART

For integral in-mold production of labeled, resin-molded containers,heretofore employed is a process of previously inserting a blank or alabel into a mold, and then molding a container in the mold in a mode ofinjection molding, blow molding, differential pressure molding or foammolding to thereby label the container (e.g., JP-A-58-69015). As suchin-mold labels, known are gravure-printed resin film, offsetmulticolor-printed synthetic paper (e.g., JP-B-2-7814, JP-A-2-84319), oraluminium label produced by lining aluminium foil with polyethylene orethylene-vinyl acetate copolymer on its back and then gravure-printingthe foil on its surface.

In-mold labels are printed with product name, manufacturer name, dealername, character, bar code, instructions for use, etc., and then used forin-mold production. For printing them, employable are various printingmethods of sheet offset printing, rotary offset printing, gravureprinting, flexographic printing, letterpress printing, screen printing;but from the sharpness of the printed matters and the production costs,sheet offset printing is much used.

However, in a method for producing label-modified, resin-molded articlesaccording to an in-mold production process of using the above in-moldlabel, when the antistatic performance of the label is insufficient,then the method is defective in that it causes an electrostatic troublein label production in a low-humidity environment in winter. In alabel-printing process where in-mold labels are printed in a mode ofsheet offset printing, the sheets being processed into in-mold labelsmay have a printing trouble owing to the generation of static charges.

A sheet offset printing system is composed of three parts of a paperfeeding part, a printing part and a paper delivery part. In the paperfeeding part, the sheets to be printed are fed to the printing part oneby one, in which each sheet is printed with ink, and then the printedsheets are conveyed to the paper delivery part, and are thereafterstacked up. In the printing part, a predetermined amount of ink ismetered and fed from an ink supply to each sheet in accordance with apattern, then applied to the printing area of a printing plate with apattern, and transferred onto a rubber printing blanket for sheet offsetprinting. FIG. 1 shows a mechanism of ink transferring onto a sheet, inwhich a sheet (1) is sandwiched between a rubber blanket (2) for sheetoffset printing and a metal impression drum (3) that synchronizes withit, and ink is thus transferred onto the surface of the substrate layerof the sheet (1). When the sheet (1) is peeled from the blanket (2) forsheet offset printing, the surface of the sheet may have static chargesgenerated therearound. As a result, when the antistatic capability ofthe sheets for in-mold labels is poorer, then the sheets could not bestacked up regularly owing to the electrostatic repulsion thereof. Whenstatic charges are accumulated in the paper delivery part, it may take alot of time to stack up them owing to their repulsion and, as a result,the printing speed could not be increased and the process is thereforeinefficient.

When labels are fed into a mold with an automatic label feeder, then thestatic charges between the stacked labels could not be removed,therefore causing some problem in that two or more labels may be fed atthe same time into a mold to give irregularly-labeled, resin-moldedarticles (rejected products) or the labels would drop and could not beused efficiently.

To solve these problems, used are in-mold labels in which a kneadablelow-molecular antistatic agent is kneaded in the heat-sealable ethylenicresin layer, or those in which a low-molecular antistatic agent isapplied onto the surface of the heat-sealable ethylenic resin layer anddried to form an antistatic layer thereon.

However, the in-mold labels of both types have a drawback in that theantistatic performance thereof could not last long and its durability ispoor. In addition, the former in-mold labels have another problem inthat the antistatic agent component therein may migrate or concentratein the surface of the heat-sealable resin layer, therefore greatlyinterfere with the fusibility of the heat-sealable resin to containerswith the result that the labels could not fuse to containers at all orthe labels having fused to containers may blister.

To solve the above problems, proposed is a method of adding apolyether-ester-amide having a long-lasting non-adhesive antistaticcapability, to a heat-sealable resin (e.g., JP-A-11-352888).

However, the method has a problem in that, in a process of kneading theadditive in a heat-sealable resin and extruding it through a T-die of anextruder to produce labels, it may deposit and degrade around the outletport of the T-die to give a large amount of burr, or it may deposit onand soil the roll surface in the production line that is in contact withthe heat-sealable resin layer with the result that the burr and thedirty deposit may drop off to cause defects of the produced films, and,as a result, the production line must be frequently stopped to clean thedie tip and the roll surface.

DISCLOSURE OF THE INVENTION

An object of the invention is to provide an in-mold label for givinglabeled resin-molded articles, which has good workability in printing,cutting and blanking even in a low-humidity environment and which hasgood adhesiveness to containers, and to provide a labeled resin-moldedarticle.

We, the present inventors have assiduously studied in-mold labels havingan antistatic capability in a low-humidity environment and, as a result,have found that, when the wetting index of an olefinic resin substratelayer and a heat-sealable resin layer having an antistatic layer on itssurface, which are mentioned below, and the initial frictional chargevoltage of the olefinic resin substrate layer relative to a sheet offsetprinting blanket each are defined to fall within a specific range, thenthe above-mentioned problems can be solved.

Specifically, the invention provides an in-mold label and a labeledresin-molded article having the following constitution:

(1) An in-mold label comprising an olefinic resin substrate layer (A)and a heat-sealable resin layer (B) having an antistatic layer on itssurface, wherein the wetting index (α) of the surface of the substratelayer (A) is from 34 to 74 mN/m, the wetting index (β) of the surface ofthe heat-sealable resin layer (B) is from 30 to 54 mN/m, and theabsolute value of the initial frictional charge voltage at 23° C. and arelative humidity of 30% of the substrate layer (A) relative to a sheetoffset printing blanket is from 0 kV to 15 kV.

(2) The in-mold label of (1), wherein the half-value period of thefrictional charge voltage attenuation of the substrate layer (A) is atmost 10 seconds.

(3) The in-mold label of (1) or (2), wherein the substrate layer (A) hasa multi-layered structure and is stretched at least in the monoaxialdirection thereof.

(4) The in-mold label of any one of (1) to (3), wherein the substratelayer (A) contains a propylenic resin as the main ingredient thereof.

(5) The in-mold label of any one of (1) to (4), wherein the substratelayer (A) contains at least one of an inorganic fine powder and anorganic filler and contains voids.

(6) The in-mold label of any one of (1) to (5), wherein the substratelayer (A) has a structure that comprises a core layer of abiaxially-stretched film of a resin composition containing from 5 to 30%by weight of an inorganic fine powder, from 3 to 20% by weight of anethylenic resin and from 50 to 92% by weight of a propylenic resin, anddisposed on both surfaces thereof, a surface layer and a back layer of amonoaxially-stretched film of a resin composition containing from 35 to65% by weight of an inorganic fine powder, from 0 to 10% by weight of anethylenic resin and from 35 to 55% by weight of a propylenic resin.

(7) The in-mold label of any one of (1) to (6), wherein theheat-sealable resin layer (B) contains a high-pressure-processpolyethylene having a density of from 0.900 to 0.935 g/cm³, a degree ofcrystallinity (by X-ray diffraction method) of from 10 to 60% and anumber-average molecular weight of from 10,000 to 40,000, or a straightlinear polyethylene having a density of from 0.880 to 0.940 g/cm³.

(8) The in-mold label of any one of (1) to (7), wherein the thickness ofthe substrate layer (A) is from 20 to 500 μm, and the thickness of theheat-sealable resin layer (B) is from 1 to 100 μm.

(9) The in-mold label of any one of (1) to (8), wherein the surface ofthe substrate layer (A) has a pigment-containing coating layer.

(10) The in-mold label of any one of (1) to (9), wherein the surface ofthe substrate layer (A) is subjected to surface activation treatment.

(11) The in-mold label of any one of (1) to (10), wherein an antistaticlayer is provided on the surface of the coating layer or the substratelayer (A).

(12) The in-mold label of (11), wherein the antistatic layer provided onthe surface of the coating layer or the substrate layer (A) contains anantistatic agent in an amount of from 0.001 to 10 g per a unit area(m²), and the antistatic layer on the surface of the heat-sealable resinlayer (B) contains an antistatic agent in an amount of from 0.001 to 1 gper a unit area (m²).

(13) The in-mold label of (12), wherein the antistatic agent contains apolymer antistatic agent.

(14) The in-mold label of any one of (1) to (13), wherein the antistaticlayer is provided according to one or more selected from die, bar, roll,gravure, spray, blade, air knife and size press coating systems.

(15) A labeled resin-molded article with an in-mold label of any one of(1) to (14) stuck to a thermoplastic resin container.

(16) The labeled resin-molded article of (15), wherein the adhesionstrength between the in-mold label and the thermoplastic resin containeris at least 200 gf/15 mm.

The in-mold label of the invention may well be processed for printing,cutting and blanking even in a low-humidity environment. In the labeledresin-molded article of the invention, the adhesion strength of thelabel to the container is high.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a mechanism of sheet offset printing.

FIG. 2 is a view showing a friction element in a frictional chargevoltage meter.

FIG. 3 is a view showing the measurement mechanism of a frictionalcharge voltage meter.

In these drawings, 1 is a sheet; 2 is a blanket for sheet offsetprinting; 3 is an impression drum; 4 is a friction element; 5 is anolefinic resin substrate layer; 6 is a heat-sealable resin layer; 7 isan in-mold label; 8 is a friction bed; 9 is a sample table, 10 is asample holder.

BEST MODE FOR CARRYING OUT THE INVENTION

The in-mold label and the labeled resin-molded article of the inventionare described in detail hereinunder. In this description, the numericalrange expressed by the wording “a number to another number” means therange that falls between the former number indicating the lowermostlimit of the range and the latter number indicating the uppermost limitthereof.

The in-mold label of the invention comprises an olefinic resin substratelayer (A) and a heat-sealable resin layer (B) having an antistatic layeron its surface. The wetting index (α) of the surface of the substratelayer (A) is from 34 to 74 mN/m, the wetting index (β) of the surface ofthe heat-sealable resin layer (B) is from 30 to 54 mN/m. The absolutevalue of the initial frictional charge voltage of the surface of thesubstrate (A), as measured using a sheet offset printing blanket andaccording to the frictional charge voltage attenuation measuring methoddescribed in JIS L 1094, falls within a range of from 0 kV to 15 kV.

The substrate layer (A) must have ink acceptability in various printingsystems of sheet offset printing, rotary offset printing, gravureprinting, flexographic printing, letter-press printing, screen printingand the like, and therefore the wetting index of the surface of thesubstrate layer (A) is from 34 to 74 mN/m, preferably from 42 to 72mN/m. If the surface wetting index of the substrate layer (A) is lessthan 34 mN/m, then the ink acceptability of the layer is insufficientand the printing ink may drop off during blow molding; but if largerthan 74 mN/m, then the labels may stick together at their edges duringblanking, and they will be difficult to insert into a mold one by oneduring blow molding.

The heat-sealable resin layer (B) must satisfy sufficient adhesivenessbetween the label and a resin-molded article. For this, the surfacewetting index of the heat-sealable resin layer (B) is from 30 to 54mN/m, preferably from 34 to 52 mN/m. When the index is 30 mN/m or more,then the affinity between the label and a resin-molded article may behigh and the adhesion strength therebetween is practically useful; butif more than 54 mN/m, then the surface polarity may be too high with theresult that the adhesiveness between the label and a resin-moldedarticle may be insufficient and the label may readily peel off. Thewetting index as referred to in this description is a value measuredaccording to “JIS K 6768 (1999): Wet Tensile Strength Test Method forPlastic Films and Sheets”.

The antistatic agent to constitute the antistatic layer of theheat-sealable resin layer (B) may be any of a low-molecular antistaticagent, polymer antistatic agent, an electron-conductive antistaticagent, a conductive filler. The low-molecular antistatic agent includesglycerin fatty acid esters, alkylsulfonate salts, tetraalkylammoniumsalts, alkylbetaines. the polymer antistatic agent includes quaternarynitrogen-containing acrylic polymers, polyethylene oxides, polyethylenesulfonate salts, carbobetaine graft copolymers. The electron-conductiveantistatic agent includes polypyrrole, polyaniline. The conductivefiller includes tin oxide, zinc oxide. Above all, those containing apolymer antistatic agent are preferred. The antistatic capability of theheat-sealable resin layer (B) is necessary for preventing troubles ofirregular delivery of printed sheets in the paper delivery part in asheet offset printing process and sticking of labels in a blankingprocess.

The antistatic capability of the in-mold label may be evaluated bymeasuring the initial frictional charge voltage and the half-valueperiod of frictional charge voltage attenuation thereof. During sheetoffset printing, a sheet (1) is sandwiched between a rubber blanket (2)for sheet offset printing and a metal impression drum (3) thatsynchronizes with it, and printed thereon, as in FIG. 1. For reproducingthe static charge having generated in the sheet in that condition, theinitial frictional charge voltage and the half-value period offrictional charge voltage attenuation of the sheet are measuredaccording to the method mentioned below, in the invention.

The measurement of the initial frictional charge voltage in theinvention is based on the frictional charge voltage attenuationmeasuring method described in 5.4 of “JIS L 1094 (1997): Method forTesting Chargeability of Fabrics and Knits”, in which a test sample ofthe in-mold label is measured. The measurement is as follows: First, arubber blanket (2) for sheet offset printing (trade name; R10 by SRIHybrid) is fixed to a friction element (4) to cover the friction surfacethereof, as in FIG. 2. Next, as in FIG. 3, an in-mold label (7) isfitted to the sample holder (10) provided on a sample table (9) in sucha manner that the olefinic resin substrate layer (5) thereof may be incontact with the friction element (4) and the heat-sealable resin layer(6) is in contact with the metallic friction bed (8), and this is fixedon the friction bed (8), and the initial charge of the in-mold label (7)and the sheet offset printing blanket (2) is discharged with adischarger. The in-mold label (7) is rubbed five times in a rate of twotimes per second all in one direction, and immediately after thus rubbedfive times, the in-mold label (7) is rapidly moved to the lower part ofa charge receiver in which the charge voltage and its attenuation curveof the sample are recorded. From the curve, the initial frictionalcharge voltage and the half-value period of frictional charge voltageattenuation of the sample are determined. The charge receiver is so setthat the distance between the charge receiver and the in-mold label (7)moved to it could be 50 mm. The measurement is carried out in anenvironment at 23° C. and a relative humidity of 30%.

Either positive or negative, a larger value of the frictional chargevoltage indicates that the tested sample is more readily chargedstatically. If the value is too large, then it causes troubles inprinting and processing the label. A longer half-value period offrictional charge voltage attenuation means that the tested sample ismore difficult to discharge. If the half-value period is too long, thenit also causes troubles in printing and processing the label.

When the absolute value of the initial frictional charge voltagemeasured according to the above method is more than 15 kV, then itcauses some problems in that the labels may be irregularly delivered inthe delivery part in sheet offset printing, and that the static chargebetween the stacked labels could not be removed in feeding them into amold by the use of an automatic label feeder, therefore resulting inthat two or more labels may be simultaneously fed into a mold to giverejected products of resin-molded articles. Accordingly, the absolutevalue of the initial frictional charge voltage must be within a range offrom 0 kV to 15 kV, preferably from 0 kV to 13 kV, more preferably from0 kV to 10 kV.

When the half-value period of frictional charge voltage attenuation istoo long, then it is inefficient since a lot of time is taken forregularly stacking up the sheets in the paper delivery part in sheetoffset printing and the printing speed could not be increased.Accordingly, the half-value period of frictional charge voltageattenuation is preferably at most 10 seconds, more preferably at most 8seconds, even more preferably at most 6 seconds.

Specifically, the invention has been completed on the basis of thefinding that the static charge generation caused by the friction betweenan in-mold label and an offset printing blanket and thereforeproblematic for in-mold labels can be effectively prevented by providingan antistatic layer on the surface of the heat-sealable resin layer (B),or that is, the back of the label, not on the side of the substratelayer (A), or that is, the surface of the label, and the initialfrictional charge voltage and the attenuation time for the frictionalcharge voltage of the label can be thereby reduced, and the finding thatthe printability and the adhesion strength of the label can be improvedby specifically defining the wetting index of both the surface and theback of the label.

The substrate layer (A) constituting the in-mold label of the inventioncontains an olefinic resin as the essential ingredient thereof. Theolefinic resin to be used in the substrate layer (A) includes propylenicresin, high-density polyethylene, middle-density polyethylene,polymethyl-1-pentene, ethylene-cyclic olefin copolymer. Two or morethese resins may be mixed for use herein. The olefinic resin substratelayer (A) may have a multi-layered structure. It may have a two-layeredstructure comprising a core layer (c) and a surface layer (D); or athree-layered structure comprising a core layer (C) and a surface layer(D) and a back layer (E) provided on the surface and the back of thecore layer; or may have a more multi-layered structure additionallyhaving any other resin film layer between the back/surface layer and thecore layer (C).

Preferably, the film to constitute the substrate layer (A) is stretchedat least in the monoaxial direction thereof. In case where the substratelayer (A) is formed of plural layers, then at least one of the layers ispreferably stretched. In case where plural layers are stretched, theymay be individually stretched before laminated; or after laminated, theresulting laminate may be stretched. Stretched layers may be againstretched after laminated. After the heat-sealable resin layer (B) isformed on the substrate layer (A), the whole may be stretched.

Various known methods may be used for the stretching. Preferred is rollstretching to be attained by utilizing the peripheral speed differencebetween plural rolls. According to the method, the stretching draw ratiomay be controlled in any desired manner. In addition, since the resinmay be stretched and oriented in the machine direction of film, labelshaving a higher tensile strength and undergoing smaller dimensionalchange by tension during printing may be obtained as compared with thoseof unstretched film. The stretching temperature may be not lower thanthe glass transition point of the olefinic resin used, when the film isformed of an amorphous resin; and when the film is formed of acrystalline resin, then the stretching temperature may be from the glasstransition point of the amorphous part to the melting point of thecrystalline part of the film.

The heat-sealable resin layer (B) is so constituted that the adhesionstrength between the label of the invention and an in-mold shapedarticle of a thermoplastic resin container is preferably at least 200gf/15 mm, more preferably at least 350 gf/15 mm, even more preferablyfrom 450 to 1000 gf/15 mm. If the adhesion strength is too low, then thelabel may peel off owing to the impact given thereto duringtransportation of contents-filled, labeled thermoplastic resincontainers or during display of products.

Preferably, the substrate layer (A) in the invention has a melting pointhigher by at least 15° C. than the melting point of the polyolefinicresin that constitutes the heat-sealable resin layer (B); andpreferably, it is formed of a propylenic resin in view of its chemicalresistance and cost. The propylenic resin may be a propylene homopolymerhaving isotactic or syndiotactic stereospecificity, or a propylene-basedcopolymer with an α-olefin such as ethylene, butene-1, hexene-1,heptene-1, 4-methylpentene-1. The copolymer may be a binary, ternary orquaternary copolymer, or may be a random or block copolymer.

Preferably, the substrate layer (A) contains at least one of aninorganic fine powder and an organic filler in addition to the olefinicresin, and contains voids. The inorganic fine powder may have a meanparticle size of generally from 0.01 to 15 μm, preferably from 0.01 to 8μm, more preferably from 0.03 to 4 μm. Concretely, it includes calciumcarbonate, calcined clay, silica, diatomaceous earth, talc, titaniumoxide, barium sulfate, alumina.

The organic filler may have a mean particle size, after dispersed, ofgenerally from 0.01 to 15 μm, preferably from 0.01 to 8 μm, morepreferably from 0.03 to 4 μm. Preferably, a resin different from theessential ingredient, olefinic resin is selected for the organic filler.For example, usable are polyethylene terephthalate, polybutyleneterephthalate, polycarbonate, nylon-6, nylon-6,6, homopolymer of cyclicolefin and copolymer of cyclic olefin with ethylene, having a meltingpoint of from 120° C. to 300° C. or a glass transition temperature offrom 120° C. to 280° C. Further if desired, the substrate layer (A) maycontain a stabilizer, a light stabilizer, a dispersant, a lubricant, afluorescent brightener, a colorant.

Of the above, the substrate layer (A) is preferably formed of astretched, porous resin film that comprises a core layer (C) of abiaxially-stretched film of a resin composition containing from 5 to 30%by weight of an inorganic fine powder, from 3 to 20% by weight of anethylenic resin and from 50 to 92% by weight of a propylenic resin; asurface layer (D) of a monoaxially-stretched film of a resin compositioncontaining from 35 to 65% by weight of an inorganic fine powder, from 0to 10% by weight of an ethylenic resin and from 35 to 55% by weight of apropylenic resin, stuck to one surface of the core layer (C); and a backlayer (E) of a monoaxially-stretched film of a resin compositioncontaining from 35 to 65% by weight of an inorganic fine powder, from 0to 10% by weight of an ethylenic resin and from 35 to 55% by weight of apropylenic resin, stuck to the other surface of the core layer (C) onthe opposite side thereof to the surface layer (D), in view of thedimensional stability of the label in printing, the feedability thereofto mold and the thermal shrinkage resistance thereof.

The stretched resin film is printed on the side of the surface layer (D)thereof; and the heat-sealable resin layer (B) is disposed on the sideof the back layer (E) thereof. Preferably, the density of the stretched,porous resin film is within a range of from 0.65 to 1.02 g/cm³.

Not specifically defined in point of the type thereof, the resin toconstitute the heat-sealable resin layer (B) may be any one having thefunction of sticking to the resin material that constitutes a containerto which the label is to be stuck under heat in in-mold production ofthe container. Preferred examples of the resin are polyethylenic resinshaving a melting point of from 80 to 130° C., for example, low-densityto middle-density, high-pressure-process polyethylene having a densityof from 0.900 to 0.935 g/cm³, straight linear polyethylene having adensity of from 0.880 to 0.940 g/cm³, and ethylene-vinyl acetatecopolymer, ethylene-acrylic acid copolymer, ethylene-alkyl acrylatecopolymer, ethylene-alkyl methacrylate copolymer (the alkyl group hasfrom 1 to 8 carbon atoms), metal salt (e.g., Zn, Al, Li, K, Na) ofethylene-methacrylic acid copolymer.

Of those, preferred are high-pressure-process polyethylene or straightlinear polyethylene having the above-mentioned density and having adegree of crystallinity (by X-ray diffraction method) of from 10 to 60%and a number-average molecular weight of from 10,000 to 40,000. Aboveall, most preferred is straight linear polyethylene obtained throughcopolymerization of from 40 to 98% by weight of ethylene and from 2 to60% by weight of an α-olefin having from 3 to 30 carbon atoms in thepresence of a metallocene catalyst (especially, a metallocene-alumoxanecatalyst, or a catalyst comprising metallocene compound and a compoundcapable of reacting with a metallocene compound to form a stable anion,as in WO92/01723), in view of its adhesiveness to resin-molded articles.One or more such polyolefinic resins may be used herein either singly oras mixed.

If desired, the heat-sealable resin layer (B) may be embossed. Whenembossed, the surface of the heat-sealable resin layer (B) is roughened,and it may prevent blistering in in-mold production of labeled products.

Any other known additives to resin may be optionally added to theheat-sealable resin layer (B) in the invention, not detracting from thenecessary properties of the heat-sealable resin layer. The additivesinclude dye, nucleating agent, plasticizer, release agent, antioxidant,antiblocking agent, flame retardant, UV absorbent.

The heat-sealable resin layer (B) may be formed according to a method oflaminating a heat-sealable resin film on the substrate layer (A) tothereby form the intended heat-sealable resin layer thereon; or a methodthat comprises applying an emulsion of a heat-sealable resin or a resinliquid that has been prepared by dissolving a heat-sealable resin in asolvent such as toluene or ethyl cellosolve, onto the substrate layer(A), and then drying it to form the intended heat-sealable resin layerthereon.

The thickness of the substrate layer (A) may be from 20 to 500 μm,preferably from 40 to 200 μm. If the layer is too thin, then it maycause some problems in that the label could not be fixed in the regularposition when inserted into a mold by the use of a label inserter, orthe label may be wrinkled. If too thick on the contrary, then thestrength of the boundary part between the in-mold produced, resin-moldedarticle and the label may lower, and the dropping resistance of theresin-molded article may be poor. The thickness of each constitutivelayer may be as follows: The layer (C) is preferably from 19 to 170 μm(more preferably from 38 to 130 μm); the layer (D) is preferably from 1to 40 μm (more preferably from 2 to 35 μm); the layer (E) is preferablyfrom 1 to 40 μm (more preferably from 1 to 35 μm).

Preferably, the thickness of the heat-sealable resin layer (B) is from 1to 100 μm, more preferably from 2 to 20 μm. The heat-sealable resinlayer (B) must be melted by the heat of the polyethylene or propylenicresin melt that is usable as a parison in molding, whereby the label andthe resin-molded article must fuse together; and in order to obtain asufficient adhesion strength between them, the thickness of theheat-sealable resin layer (B) is preferably at least 1 μm. On the otherhand, if the thickness of the layer is more than 100 μm, then the labelmay curl and its sheet offset printing would be difficult, and, inaddition, it would also be difficult to fix the label in a mold.

For improving the printability thereof, the surface of the substratelayer (A) may have a pigment-containing coating layer formed thereon.The pigment-coating layer may be formed by applying pigment to the layeraccording to an ordinary coating method for coated paper. Thepigment-coating agent to be used for the pigment coating may be anyordinary latex for coated paper, which may comprise from 30 to 80% byweight of pigment such as clay, talc, calcium carbonate, magnesiumcarbonate, aluminium hydroxide, silica, calcium silicate, plasticpigment, and from 20 to 70% by weight of adhesive.

The adhesive for the above includes latex such as SBR (styrene-butadienecopolymer rubber), MBR (methacrylate-butadiene copolymer rubber); andacrylic emulsion, starch, PVA (polyvinyl alcohol), CMC (carboxymethylcellulose), methyl cellulose. The composition may contain a dispersant,for example, specific polysodium carboxylate such as acrylic acid-sodiumacrylate copolymer; and a crosslinking agent such as polyamide-urearesin. The pigment-coating agent is used as a water-soluble coatingagent generally having a solid matter concentration of from 15 to 70% byweight, preferably from 35 to 65% by weight.

The surface of the substrate layer (A) or the coating layer may beactivated. The activation treatment may be at least one treatmentselected from corona discharge treatment, flame treatment, plasmatreatment, glow discharge treatment, ozone treatment, preferably coronatreatment or flame treatment. In case of corona treatment, the degree oftreatment may be from 600 to 12,000 J/m² (from 10 to 200 W·min/m²),preferably from 1200 to 9000 J/m² (from 20 to 150 W·min/m²). If smallerthan 600 J/m² (10 W·min/m²), then the corona discharge treatment may beineffective with the result that, in the subsequent process of applyingan aqueous, antistatic agent-containing solution to the layer, thesolution may be repelled away; but even if larger than 12,000 J/m² (200W·min/m²), the effect of the treatment could not increase anymore.Accordingly, the degree of treatment of at most 12,000 J/m² (200W·min/m²) is enough. In case of flame treatment, the degree of treatmentmay be from 8,000 to 200,000 J/m², preferably from 20,000 to 100,000J/m². If smaller than 8,000 J/m², then the flame treatment may beineffective with the result that, in the subsequent process of applyingan aqueous, antistatic agent-containing solution to the layer, thesolution may be repelled away; but even if larger than 200,000 J/m², theeffect of the treatment could not increase any more. Accordingly, thedegree of treatment of at most 200,000 J/m² is enough. If desired, thesurface of the heat-sealable resin layer (B) may also undergo the aboveactivation treatment.

After the surface of the coating layer or the substrate layer (A) isactivated as above, it is desirable that the above antistatic layer isprovided thereon. Providing the antistatic layer further improves thepaper introduction and delivery in printers.

In the invention, when an antistatic layer is provided on the surface ofthe coating layer or the substrate layer (A), the antistatic layer maycontain an antistatic agent in an amount of from 0.001 to 10 g as thesolid matter content thereof per a unit area (m²), preferably from 0.002to 8 g, more preferably from 0.002 to 5 g, even more preferably from0.005 to 0.1 g. If the amount of the antistatic agent is less than 0.001g, then the antistatic effect would be insufficient; but if more than 10g, then the ink acceptability of the layer would be insufficient and theprinting ink may drop off during blow molding. Similarly, the antistaticlayer on the heat-sealable resin layer (B) may contain an antistaticagent in an amount of from 0.001 to 1 g as the solid matter contentthereof per a unit area (m²), preferably from 0.002 to 0.8 g, morepreferably from 0.005 to 0.5 g. If the amount of the antistatic agent isless than 0.001 g, then the antistatic effect would be insufficientsimilarly to the above; but if more than 1 g, then the adhesion strengthbetween the heat-sealable resin layer (B) and the resin-molded articlemay lower.

The antistatic layer in the invention may be formed, for example, byapplying an aqueous solution that contains a polymer antistatic agentalone having the following constitution (a) or further contains, asmixed with it, an ink-receiving component of (b) or (c), onto the layerand drying it thereon.

Component (a): tertiary or quaternary nitrogen-containing acrylicpolymer, 100% by weight.Component (b): polyimine compound, from 0 to 300% by weight.Component (c): polyamine-polyamide/epichlorohydrin adduct, from 0 to300% by weight.

The tertiary or quaternary nitrogen-containing acrylic polymer of thecomponent (a) may be obtained through copolymerization of monomers offrom 4 to 94% by weight of the following component (i), from 6 to 80% byweight of the following component (ii) and from 0 to 20% by weight ofthe following component (iii).

Component (i): At Least One Monomer Selected from Compounds of theFollowing Chemical Formulae (I) to (VII):

In formulae (I) to (VII), R¹ represents a hydrogen atom or a methylgroup; R² and R³ each represent a lower alkyl group (preferably havingfrom 1 to 4 carbon atoms, more preferably 1 or 2 carbon atoms); R⁴represents a saturated or unsaturated alkyl or cycloalkyl group havingfrom 1 to 22 carbon atoms; X⁻ represents a quaternated counter anion toN⁺(e.g., halide, especially chloride); M represents an alkali metal ion(e.g., sodium, potassium); A represents an alkylene group having from 2to 6 carbon atoms.

Of those monomers, preferred are the compounds of formula (VI).

Component (ii): (meth)acrylate:

In the above formula, R¹ represents a hydrogen atom or a methyl group;R⁵ represents an alkyl, alkylene or cycloalkyl group having from 1 to 24carbon atoms. Concretely, the compound includes butyl acrylate, caprylacrylate, stearyl methacrylate.

Component (iii): Other Hydrophobic Vinyl Monomer.

Examples of the hydrophobic vinyl monomer are styrene and vinylchloride.

Of the above-mentioned, tertiary nitrogen or quaternarynitrogen-containing acrylic polymer of the component (a), especiallypreferred is a water-soluble polymer having good antistatic capabilityof the monomer (i) of formula (VI) where X⁻ is Cl⁻; and its commercialproducts are sold by Mitsubishi Chemical as trade names of SuftomerST-1000, Suftomer ST-1100, Suftomer ST-1300, Suftomer ST-3200.

Component (b): Polyimine Compound, from 0 to 300% by Weight.

The polyimine compound of the component (b) is a primer for enhancingthe adhesion strength of the layer. For example, it includes polyiminecompounds selected from a group consisting of polyethyleneimine,polyaminepolyamide-ethyleneimine adduct, and their alkyl-modified,alkenyl-modified, benzyl-modified or alicyclic hydrocarbon-modifiedderivatives with a halide serving as a modifier, such as an alkylhalide, an alkenyl halide, a cycloalkenyl halide or benzyl halide havingfrom 1 to 24 carbon atoms serving, having a degree of polymerization offrom 200 to 3,000 and represented by the following formula (IX), andpoly(ethyleneimine-urea). These are described in detail in JP-B-2-2910,and JP-A-1-141736.

In the formula, z represents —NH—R⁹ or a polyaminepolyamide residue; R⁶to R⁹ each independently represent a hydrogen atom, an alkyl group, analkenyl group, a cycloalkyl group or a benzyl group having from 1 to 24carbon atoms, at least one of them is a group except hydrogen; mindicates a numerical value of from 0 to 300; and n, p and q eachindicate a numerical value of from 1 to 300.

Component (c): Polyamine-Polyamide/Epichlorohydrin Adduct, from 0 to300% by Weight.

The polyamine-polyamide/epichlorohydrin adduct of the component (c) isalso a primer for enhancing the adhesion strength of the layer. Itincludes a water-soluble cationic thermosetting resin obtained throughreaction of a polyamide, which is prepared from a saturated dibasiccarboxylic acid having from 3 to 10 carbon atoms and apolyalkylene-polyamine, with epichlorohydrin. The details of such athermosetting resin are described in JP-B-35-3547. A specific example ofthe saturated dibasic carboxylic acid having from 3 to 10 carbon atomsis a dicarboxylic acid having from 4 to 8 carbon atoms, especiallyadipic acid.

An example of the polyalkylene-polyamine is a polyethylene-polyamine,including ethylenediamine, diethylenetriamine, triethylenetetramine,especially diethylene triamine.

In addition to these components, for example, a water-soluble inorganiccompound such as sodium carbonate, sodium sulfate, sodium sulfite,sodium thiosulfate, barium hydroxide, sodium metasilicate, sodiumpyrophosphate, sodium tripolyphosphate, sodium primary phosphate,potassium alum, ammonium alum, ammonia; a water-soluble organic solventsuch as ethyl alcohol, isopropyl alcohol; a surfactant; a water-solublepolymerization agent such as ethylene glycol, polyvinyl alcohol; andother auxiliary materials may be optionally added to the layer.

The blend ratio of the components (a), (b) and (c) may be as follows:Relative to 100% by weight of the nitrogen-containing acrylic resin (a),the polyimine compound (b) is from 0 to 300% by weight, preferably from0 to 200% by weight, and the polyamine-polyamide/epichlorohydrin adduct(c) is from 0 to 300% by weight, preferably from 0 to 200% by weight.When the antistatic layer has the composition as above, then the surfaceof the olefinic resin substrate layer and/or the surface of theheat-sealable resin layer are hardly statically charged, and the paperintroduction and delivery may be good. These components (a), (b) and (c)may be used as an aqueous solution thereof having an overall solidmatter content of generally from 0.1 to 10% by weight, preferably from0.1 to 5% by weight.

For applying the above-mentioned, aqueous antistatic agent solution(coating agent) onto the surface of the heat-sealable resin layer (B) orthe surface of the substrate layer (A) or the coating layer, employableis any coating method of die, bar, roll, gravure, spray, blade, airknife or size press coating, or their combination. Depending on theviscosity of the coating agent, the coating amount and the coatingspeed, a predetermined amount of the coating agent is measured, using adie, a roll, a gravure or a spray, and transferred onto a roll or a sizepress and applied to the object; or a larger amount than a predeterminedamount of the coating agent is transferred using a die or a roll, andthen the excessive coating agent is scraped off with a bar, a blade oran air knife to thereby make the predetermined amount of the coatingagent applied onto the object; or a predetermined amount of the coatingagent may be directly applied onto the object, using a die or a spray.More concretely, for a coating mode where a coating agent having aviscosity of from 10 to 1000 cP (from 0.01 to 1 Ns/m²) is applied ontothe object to a coating amount of from 1 to 20 g/m² at a coating speedof at most 300 m/sec, an offset gravure system, a spray system or arotor dampening system may be employed. The offset gravure system is acombination of gravure coating and roll coating, in which the coatingagent is transferred from a gravure plate to a roll, and while theliquid is transferred from one roll to another, the gravure plate formis removed and the coating agent is smoothed, and thereafter the agentis transferred onto the surface of each layer. In a spray system wherespraying and size-pressing are combined, the coating agent is fed from asupply unit to a spray-coating unit to thereby form a uniform coatingfilm before the size press, and this is then transferred from the sizepress to the heat-sealable resin layer. Accordingly, this method isfavorable in applying a small amount of the coating agent to the layer.Rotor dampening is a type of spray coating, and the method comprisesatomizing the coating agent with a rotor that is driven by a belt torotate rapidly, and directly applying the resulting mist to the surfaceof each layer.

After coated with the coating agent, the coated layer may be furtheroptionally smoothed or dried to thereby remove any excess water andhydrophilic solvent, and the intended antistatic layer is thus formedthereon.

The in-mold label is set in a differential-pressure molding mold in sucha manner that its printed surface faces the inner face of the lowerfemale mold part, then it is fixed to the inner wall of the mold bysuction, and thereafter a melt of a container-forming material resinsheet is led to the area above the lower female mold part and is moldedaccording to an ordinary differential-pressure molding process, wherebya labeled resin-molded article is formed in which the label isintegrally fused to the outer wall of the container. Thedifferential-pressure molding may be any of vacuum molding or pressuremolding. In general, the two are combined, and preferably furthercombined with plug-assisted technology for differential-pressuremolding. The in-mold label is especially favorable for blow molding inwhich a resin melt parison is fitted by pressure to the inner wall of amold. To that effect, the labeled resin-molded article is produced asfollows: The label is fixed in a mold, and the label is integrated withthe resin-molded article, in which, therefore the label is not deformedand the adhesion strength between the resin-molded article body and thelabel is high. Thus produced, therefore, the label-modified,resin-molded article has no blister and has good outward appearance.

The material of the thermoplastic resin container is not specificallydefined. For example, usable are ethylene homopolymers such ashigh-density polyethylene, middle-density polyethylene, linearlow-density polyethylene, ultra-low-density polyethylene producedthrough polymerization with a single-site catalyst; polyolefinic resinssuch as ethylene-α-olefin copolymer, branched low-density polyethylene,ethylene-vinyl acetate copolymer, polypropylene; and other polyethyleneterephthalate resin, polyethylene naphthalate resin, polyamide resin,polyvinyl chloride resin, polystyrenic resin, polycarbonate resin. Inaddition, blends of plural resins including the above-mentioned resinsare also usable. Further, those that contain an inorganic filler and anyother modifier or color pigment are also usable. The layer constitutionmay be any of a single-layered or multi-layered one. For example, abarrier resin layer of a saponified ethylene-vinyl acetate copolymer ora polyamide resin, and also an adhesive resin layer for the layer to thebasic layer may also be laminated.

The characteristics of the invention are described more concretely withreference to the following Examples and Comparative Examples. In thefollowing Examples, the material used, its amount and the ratio, thedetails of the treatment and the treatment process may be suitablymodified or changed not overstepping the sprit and the scope of theinvention. Accordingly, the invention should not be limitativelyinterpreted by the Examples mentioned below.

EXAMPLE 1 Production of Substrate Layer

A resin composition (C) comprising 67% by weight of a polypropylenehomopolymer (trade name by Nippon Polypro, Novatec PP MA-8, having amelting point of 164° C.), 10% by weight of a high-density polyethylene(trade name by Nippon Polyethylene, Novatec HD HJ580, having a meltingpoint of 134° C.), and 23% by weight of calcium carbonate powder havinga mean particle size of 1.5 μm was melt-kneaded at 250° C. in anextruder, and extruded out through a die into a film. This was cooled toabout 50° C. The film was re-heated at about 150° C., and then stretched4-times in the machine direction by utilizing the peripheral speeddifference between rolls. A monoaxially stretched film to be a core wasthus obtained.

On the other hand, a resin composition (D) comprising 51.5% by weight ofa polypropylene homopolymer (trade name by Nippon Polypro, Novatec PPMA-3), 3.5% by weight of a high-density polyethylene (trade name byNippon Polyethylene, Novatec HD HJ580), 42% by weight of calciumcarbonate powder having a mean particle size of 1.5 μm, and 3% by weightof titanium oxide powder having a mean particle size of 0.8 μm wasmelt-kneaded at 240° C. in a different extruder, and this was filmwiseextruded out through a die and laminated onto the surface of theabove-mentioned, monoaxially-stretched film to obtain a laminate ofsurface layer/core layer (D/C).

Further, also using different extruders, a composition (E) comprising51.5% by weight of a polypropylene homopolymer (trade name by NipponPolypro, Novatec PP MA-3), 3.5% by weight of a high-density polyethylene(trade name by Nippon Polyethylene, Novatec HD HJ580), 42% by weight ofcalcium carbonate powder having a mean particle size of 1.5 μm, and 3%by weight of titanium oxide powder having a mean particle size of 0.8μm; and, as a heat-sealable resin layer, a mixture (B) comprising 75parts by weight of an ethylene/1-hexane copolymer (having a 1-hexenecontent of 22% by weight, a degree of crystallinity of 30, and anumber-average molecular weight of 23,000), which had been obtainedthrough copolymerization of ethylene and 1-hexene with a metallocenecatalyst and had MFR of 18 g/10 min and a density of 0.898 g/cm³, and 25parts by weight of a high-pressure-process low-density polyethylenehaving MFR of 4 g/10 min, a density of 0.92 g/cm³, a degree ofcrystallinity (by X-ray diffraction method) of 40% and a number-averagemolecular weight of 18,000 were melted and kneaded at 200° C., and fedinto one coextrusion die in which they were laminated, and they werefilmwise extruded out through the die, whereby they were furtherlaminated on the above laminate (D/C) in such a manner that theheat-sealable resin layer could be the outermost layer on the side ofthe core layer, thereby producing a four-layered laminate of surfacelayer/core layer/back layer/heat-sealable resin layer (D/C/E/B). Theresulting laminate was led onto an embossing roll (150 lines/inch;reversed gravure pattern) composed of a metal roll and a rubber roll onthe layer B side thereof, whereby the heat-sealable resin layer (B) wasembossed with a 0.17 mm-pitch pattern.

The four-layered laminate was led into a tenter oven, heated at 155° C.,then stretched 7-fold in the cross direction by the use of the tender,then annealed at 164° C. and thereafter cooled to 55° C., and its edgeswere trimmed away. Then, this was subjected to corona dischargetreatment at 50 W/m²/min on the side of the surface layer (D) thereof.Next, an aqueous solution containing 0.5% by weight of the following(a), 0.4% by weight of (b) and 0.5% by weight of (c) was applied to thesurface layer side of the film according to a size-pressing system insuch a manner that the coating layer could contain, after dried, 0.01 gper a unit area (m²) of the antistatic agent. Then, an aqueous solutioncontaining the following (a) was sprayed onto the side of theheat-sealable resin layer (B) in such a manner that the coating layercould contain, after dried, 0.01 g per a unit area (m²) of theantistatic agent. After dried, the antistatic layer was thus formed onboth the surface layer and the back layer of the film.

(a) Quaternary nitrogen-containing acrylic tercopolymer comprising thefollowing units:

(b) Butyl-modified polyethylenimine (AC-72, trade name by MitsubishiChemical).(c) Water-soluble polyamine-polyamide/epichlorohydrin adduct (WS-4002,trade name by Seiko PMC).

The wetting index of the surface of the olefinic resin substrate layer(A, or that is, D/C/E) and the surface of the heat-sealable resin layer(B) were measured, and were 70 mN/m and 34 mN/m, respectively.

Accordingly, a six-layered, laminated stretched resin film having athickness of about 100 μm (antistatic layer/D/C/E/B/antistatic layerultra-thin/30/40/25/5 ultra-thin μm; as a result of electromicroscopicobservation of the cross section of the film) was obtained.

The six-layered, laminated stretched resin film was cut with a sheetcutter into kiku-half size (636 mm×470 mm) sheets for in-mold labels.

<Printing>

Thus obtained, the in-mold label sheets were printed on the surface sidethereof in an environment at 23° C. and a relative humidity of 30%,using an offset printer, Komori Corporation 's Lithlon and UV offsetink, T&K TOKA's Bestcure, at a speed of 6000 sheets/hr. The UV offsetfour-color print on them includes product name, manufacturer name,dealer name, character, bar code and instructions for use. The sheetswere well regularly stacked up in the paper delivery part, and theiracceptability of every ink was good.

<Blanking>

Next, the thus-printed sheets for in-mold labels were blanked out intoin-mold labels having a length of 11 cm and a width of 9 cm. The cutedges of the labels were checked for blocking, and no blocking was foundtherearound.

<Sticking>

The in-mold label was fixed in one half of a split mold for blowmolding, in such a manner that its surface layer side could be incontact with the mold under vacuum suction, and then a high-densitypolyethylene (Nippon polyethylene's trade name, Novatec HD HB330, havinga melting point of 134° C.) was melt-extruded at 220° C. into the moldto form a parison. With that, the split mold was closed, and a pressureof 4.2 kg/cm² was applied to the parison so that the parison wasinflated to be a container while thermally fused with the in-mold labelin the mold. After thus molded, the mold was cooled, and then opened toobtain a labeled resin container having a capacity of 1000 ml. Of theresin container, the label print did not fade and the label did neithershrink nor blister.

EXAMPLE 2

An in-mold label and a labeled resin container were produced in the samemanner as in Example 1, for which, however, the antistatic layer on theside of the heat-sealable resin layer (B) was formed by applying anaqueous solution containing the quaternary nitrogen-containing acrylictercopolymer (a) in such a manner that the layer could contain, afterdried, 0.1 g per a unit area (m²) of the antistatic agent. The wettingindex of the surface of the olefinic resin substrate layer (A) and thatof the heat-sealable resin layer (B) were 70 mN/m and 50 mN/m,respectively.

EXAMPLE 3

An in-mold label and a labeled resin container were produced in the samemanner as in Example 1, for which, however, the antistatic layer on theside of the heat-sealable resin layer (B) was formed by applying anaqueous solution containing 1.0% by weight of the quaternarynitrogen-containing acrylic tercopolymer (a) and 0.5% by weight of thewater-soluble polyamine-polyamide/epichlorohydrin adduct (c) (SeikoPMC's trade name WS-4002) in such a manner that the layer could contain,after dried, 0.01 g per a unit area (m²) of the antistatic agent. Thewetting index of the surface of the olefinic resin substrate layer (A)and that of the heat-sealable resin layer (B) were 70 mN/m and 38 mN/m,respectively.

EXAMPLE 4

An in-mold label and a labeled resin container were produced in the samemanner as in Example 1, for which, however, the antistatic layer on theside of the olefinic resin layer (A) was formed by applying an aqueoussolution containing 0.5% by weight of the quaternary nitrogen-containingacrylic tercopolymer (a), 0.4% by weight of the butylation-modifiedpolyethyleneimine (b) and 0.5% by weight of the water-solublepolyamine-polyamide/epichlorohydrin adduct (c) in such a manner that thelayer could contain, after dried, 0.002 g per a unit area (1 m²) of theantistatic agent. The wetting index of the surface of the olefinic resinsubstrate layer (A) and that of the heat-sealable resin layer (B) were48 mN/m and 34 mN/m, respectively.

COMPARATIVE EXAMPLE 1

An in-mold label and a labeled resin container were produced in the samemanner as in Example 1, for which, however, the antistatic layer was notformed on the side of the heat-sealable resin layer (B). The wettingindex of the surface of the olefinic resin substrate layer (A) and thatof the heat-sealable resin layer (B) were 70 mN/m and 32 mN/m,respectively.

COMPARATIVE EXAMPLE 2

An in-mold label and a labeled resin container were produced in the samemanner as in Example 1, for which, however, the antistatic layer on theside of the heat-sealable resin layer (B) was formed by applying anaqueous solution containing the quaternary nitrogen-containing acrylictercopolymer (a) in such a manner that the layer could contain, afterdried, 3 g per a unit area (m²) of the antistatic agent. The wettingindex of the surface of the olefinic resin substrate layer (A) and thatof the heat-sealable resin layer (B) were 70 mN/m and 62 mN/m,respectively.

TEST EXAMPLE

The in-mold labels and the labeled resin containers of Examples 1 to 4and Comparative Examples 1 and 2 were analyzed and evaluated for theirphysical properties, according to the methods mentioned below.

(1) Determination of Physical Properties: (a) Wetting Index:

The wetting index (α) of the surface of the substrate layer (A) and thewetting index (β) of the surface of the heat-sealable resin layer (B) ofeach in-mold label were measured in an environment at 23° C. and arelative humidity of 50%, using Diversified Enterprises' ACCU DYNE TEST.

(b) Initial Frictional Charge Voltage and Half-Value Period ofFrictional Charge Voltage Attenuation:

Using a frictional charge voltage meter, Kanebo Engineering's EST-8, thedata were measured according to the method mentioned above.

(2) Sheet Offset Printing: (c) Ink Acceptability:

Using an offset printer, Komori Corporation's Lithlon, 1000 kiku-halfsize (636 mm×470 mm) sheets were continuously printed in an environmentat 23° C. and a relative humidity of 30%, at a speed of 6000 sheets/hr.Next, the sheets were dried with an UV emitter, and the degree of theink adhesiveness to each sheet was determined as follows: Nichiban'sCellotape™ was stuck to each sheet, and peeled away, and the sheet waschecked for its condition and evaluated according to the followingcriteria:

◯: The ink did not peel, and the substrate layer underwent materialfracture in some samples.

Δ: There was some resistance in peeling the tape, but almost all the inkpeeled, and this is problematic in practical use.

x: All the ink peeled, and there was no resistance in peeling the tape.

(d) Paper Travelability:

Under the condition mentioned above, the sheets were printed and checkedfor their travelability in a printer. After irradiated with an UVemitter, the sheets were also checked as to whether their edges could betrued up in the delivery zone of the printer. Thus tested, the sheetswere evaluated according to the following criteria:

◯: The sheets are smoothly fed into a printer and travel therein, andtheir edges are well trued up in the delivery zone.

x: While fed, the sheets are often troubled, or their edges are nottrued up in the delivery zone.

(3) Blanking: (e) Blanking Aptitude:

100 labeled sheets were stacked up, and blanked with a rectangularblanking tool having a length of 11 cm and a width of 9 cm. The cutedges of the sheets were checked for blocking.

◯: No blocking occurred, and the samples have no problem in theirpractical use.

x: Blocking occurred, and the samples have some problem in theirpractical use.

(4) In-Mold Molding: (f) Label/Bottle Adhesion Strength:

A label stuck to a container in blow molding was cut into 15-mm widestrips. Using a tensile tester (Shimadzu Seisakusho's Autograph AGS-DModel), the adhesion strength between the label and the container wasmeasured by peeling the label from the strip in a direction forming aT-like figure at a pulling rate of 300 mm/min. The samples wereevaluated for the practicability of the label according to the followingcriteria:

More than 350 (g/15 mm): Practicable with no problem.

From 200 to 350 (g/15 mm): Somewhat week adhesiveness but practicablewith no problem.

Less than 200 (g/15 mm): Impracticable.

(g) Blistering:

Labeled blow-molded containers were compared in point of the frequencyof label blistering.

◯: Practicable with no problem.

x: Impracticable.

TABLE 1 Coating Amount of Frictional Charge Antistatic Agent Half-Value(g/m²) Period of Olefinic Heat- Initial Frictional In-Mold Molding ResinSealable Wetting Frictional Charge Label/Bottle Substrate Resin IndexCharge Voltage Sheet Offset Printing Blanking Adhesion Layer (A) Layer(B) (mN/m) Voltage Attenuation Ink Paper Blanking Strength Side Side α β(kV) (sec) Acceptability Travelability Aptitude (gf/15 mm) BlisteringExample 1 0.01 0.01 70 34 9 6 ◯ ◯ ◯ 480 ◯ Example 2 0.01 0.1 70 50 4 1 ◯◯ ◯ 380 ◯ Example 3 0.01 0.01 70 38 8 1 ◯ ◯ ◯ 460 ◯ Example 4 0.002 0.0148 34 13 7 ◯ ◯ ◯ 480 ◯ Comparative 0.01 0 70 32 17 8 ◯ X ◯ 500 ◯ Example1 Comparative 0.01 3 70 62 8 1 ◯ ◯ X 160 X Example 2

INDUSTRIAL APPLICABILITY

The in-mold label of the invention may be well printed, cut and blankedeven in a low-humidity environment. Accordingly, the in-mold label ofthe invention has the advantages of easy production and practical use.In the labeled resin-molded article of the invention, the adhesionstrength between the label and the container is high. Accordingly, thereis no trouble of label peeling in use of the article. Therefore, theinvention has a possibility of its wide utilization in the modernsociety.

1. An in-mold label comprising an olefinic resin substrate layer (A) anda heat-sealable resin layer (B) having an antistatic layer on itssurface, wherein the wetting index (α) of the surface of the substratelayer (A) is from 34 to 74 mN/m, the wetting index (β) of the surface ofthe heat-sealable resin layer (B) is from 30 to 54 mN/m, and theabsolute value of the initial frictional charge voltage at 23° C. and arelative humidity of 30% of the substrate layer (A) relative to a sheetoffset printing blanket is from 0 kV to 15 kV.
 2. The in-mold labelaccording to claim 1, wherein the half-value period of the frictionalcharge voltage attenuation of the substrate layer (A) is at most 10seconds.
 3. The in-mold label according to claim 1, wherein thesubstrate layer (A) has a multi-layered structure and is stretched atleast in the monoaxial direction thereof.
 4. The in-mold label accordingto claim 1, wherein the substrate layer (A) contains a propylenic resinas the main ingredient thereof.
 5. The in-mold label according to claim1, wherein the substrate layer (A) contains at least one of an inorganicfine powder and an organic filler and contains voids.
 6. The in-moldlabel according to claim 1, wherein the substrate layer (A) has astructure that comprises a core layer of a biaxially-stretched film of aresin composition containing from 5 to 30% by weight of an inorganicfine powder, from 3 to 20% by weight of an ethylenic resin and from 50to 92% by weight of a propylenic resin, and disposed on both surfacesthereof, a surface layer and a back layer of a monoaxially-stretchedfilm of a resin composition containing from 35 to 65% by weight of aninorganic fine powder, from 0 to 10% by weight of an ethylenic resin andfrom 35 to 55% by weight of a propylenic resin.
 7. The in-mold labelaccording to claim 1, wherein the heat-sealable resin layer (B) containsa high-pressure-process polyethylene having a density of from 0.900 to0.935 g/cm³, a degree of crystallinity (by X-ray method) of from 10 to60% and a number-average molecular weight of from 10,000 to 40,000, or astraight linear polyethylene having a density of from 0.880 to 0.940g/cm³.
 8. The in-mold label according to claim 1, wherein the thicknessof the substrate layer (A) is from 20 to 500 μm, and the thickness ofthe heat-sealable resin layer (B) is from 1 to 100 μm.
 9. The in-moldlabel according to claim 1, wherein the surface of the substrate layer(A) has a pigment-containing coating layer.
 10. The in-mold labelaccording to claim 1, wherein the surface of the substrate layer (A) issubjected to surface activation treatment.
 11. The in-mold labelaccording to claim 1, wherein an antistatic layer is provided on thesurface of the substrate layer (A) or the coating layer.
 12. The in-moldlabel according to claim 11, wherein the antistatic layer provided onthe surface of the coating layer or the substrate layer (A) contains anantistatic agent in an amount of from 0.001 to 10 g per a unit area(m²), and the antistatic layer on the surface of the heat-sealable resinlayer (B) contains an antistatic agent in an amount of from 0.001 to 1 gper a unit area (m²).
 13. The in-mold label according to claim 12,wherein the antistatic agent contains a polymer antistatic agent. 14.The in-mold label according to claim 1, wherein the antistatic layer isprovided according to one or more selected from die, bar, roll, gravure,spray, blade, air knife and size press coating systems.
 15. A labeledresin-molded article with an in-mold label of claim 1 stuck to athermoplastic resin container.
 16. The labeled resin-molded articleaccording to claim 15, wherein the adhesion strength between the in-moldlabel and the thermoplastic resin container is at least 200 gf/15 mm.